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Electronics AC Voltage Stabilizer Repaired
I received this SUN Electronic AC voltage stabilizer with no sign of life.
I opened the machine and start to test semiconductors first :
I checked transistor AO1015 it was good. For Testing the IC LM324N I decided to replace it by a good and trusted one for testing this op-amp IC require assembling a circuit on bread board and it is time consuming. I had one unused ic in stock I replaced this IC but no progress!?
Then I start to check three electrolytic capacitors by ESR meter. The ESRs were too high then I replaced them.
Now! Red led start to glow that indicated the voltages are reaching to machine, after 2-3 minutes the green LED turned on. The stable voltages must reach to outlet sockets for use.
But surprisingly no output! No voltages on outlet sockets! Machine started to work but no output there? But what else is going inside the circuit from big switch two AC line come inside the circuit one directly is connected to one of the switch poles of relay another one goes to the circuit via big polyester capacitor 650 volt 63 nano farad. 12 volt relay is installed in this machine. When the comparator IC LM324N approved the incoming AC voltages is with in tolerance give this answer by sending the 12 volt dc to another switch pols of relay. Relay lets the other line of entrance AC connect with the outlet socket wire and AC output will be ready to use. This relay when 12 VOLT DC is reaching the poles (A.B) must act as switch and poles (C.D)
Must be contacted and voltages must be appear in the output socket. I assumed that this relay must be defected component G5LA-14. I pulled this relay out of the circuit and test it. But astonishingly relay passed both testing methods outside the circuit and showed that it is working good! But inside the circuit failed to do the job.
I decided to replace the relay with a fresh one despite of this fact that relay is passed the tests and to see what will happen? And I did this and the machine start to work again and stable voltages reached to outlets! But still this is a question? Why this relay inside the circuit did not work but passed all the tests good outside the circuit?!
This article was prepared for you by Mr Beh from Iran.
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